Sarcomere dynamics during isotonic velocity transients in single frog muscle fibers

H. L.M. Granzier, A. Mattiazzi, G. H. Pollack

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

If the load on a tetanized fiber is abruptly changed to a new steady value, the ensuing fiber length change shows the well-known 'isotonic velocity transient', in which the velocity oscillates before settling at some steady value. We studied sarcomere dynamics during these transients using two methods: optical diffraction and a segment-length method. Our principal aim was to determine whether these transients might be a reflection of the fact that sarcomere shortening is often found to be stepwise. We found that pauses in sarcomere shortening occurred during the low-velocity phases of the transient and that steps of sarcomere shortening occurred during the high-velocity phases. Thus the isotonic transient appears to rise from the steps. In addition to the isotonic transient, we studied the well-known isometric transient, in which fiber length is abruptly changed, and ensuing tension response is measured. Again, we found that the transient may be a reflection of the stepwise shortening pattern.

Original languageEnglish (US)
Pages (from-to)C266-C278
JournalAmerican Journal of Physiology - Cell Physiology
Volume259
Issue number2 28-3
StatePublished - Sep 4 1990
Externally publishedYes

Keywords

  • Diffraction
  • Load clamp
  • Method
  • Pauses
  • Segment-length
  • Servo-control
  • Steps

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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